/Engine/Source/Runtime/GeometryCore/Public/DynamicMesh/MeshTangents.h
Calculate per-triangle tangent spaces based on the given per-triangle normal and UV overlays. In this mode there is no averaging of tangents across triangles. So if we have N triangles in the mesh, then 3*N tangents are generated. These tangents are computed in parallel.
void ComputeTriVertexTangents ( const [FDynamicMeshNormalOverlay](API\Runtime\GeometryCore\DynamicMesh\FDynamicMeshNormalOverlay) * NormalOverlay, const [FDynamicMeshUVOverlay](API\Runtime\GeometryCore\DynamicMesh\FDynamicMeshUVOverlay) * UVOverlay, const [FComputeTangentsOptions](API\Runtime\GeometryCore\DynamicMesh\FComputeTangentsOptions) & Options )